docs: Release notes for 2.9.11 (backport release-2.9.x) (#15288)

Co-authored-by: J Stickler <julie.stickler@grafana.com>

docs/sources/release-notes/v2-9.md

@@ -36,6 +36,13 @@ For a full list of all changes and fixes, refer to the [CHANGELOG](https://githu
  
 ## Bug fixes
 
+### 2.9.11 (2026-12-05)
+
+- **docker:** Update Docker to 23.0.15 ([#](https://github.com/grafana/loki/issues/)).
+- **lamba-promtail:** Lamba-promtail updates, some of which address CVEs([#14105](https://github.com/grafana/loki/issues/14105)).
+- **promtail:** Switch Promtail base image from Debian to Ubuntu to fix critical security issues ([#15195](https://github.com/grafana/loki/issues/15195)).
+- **storage:** Fix bug in cache of the index object client([#10585](https://github.com/grafana/loki/issues/10585)).
+
 ### 2.9.10 (2026-08-09)
 
 - Update dependencies versions to remove CVE ([#13835](https://github.com/grafana/loki/pull/13835)) ([567bef2](https://github.com/grafana/loki/commit/567bef286376663407c54f5da07fa00963ba5485)).